Renewable fuse plug



Aug. 15,-1944. E. P. BRus RENEWABLE FUSEv PLUG' Filed Sept. 4, 1942 n INVENTOR. ;77//e 1D. 5/2/5 'A TroAN Patented Aug. 15, 1944 UNITED STATES PATENT OFFICE 9 claims.

,'Ijhis invention relates to electrical fuse plugs ofthe removable type and has for its primary yobject to provide such a plug with a group of specially designed parts for holding a fusible element so as `to renew the same when necessary, all without destroying ordiscardinrg the said parts of the fuse plug assembly.

One of thermost important objects of this invention is to provide an electrical fuse plug with an unique assembly of parts, one of which is a fusible element, 'renewable by merely removing a specially designed threaded contact post, which post serves as the medium of maintaining all of the component parts of the plug in their operan tive position. l

rMinor objects of the invention are particularly important and include specific 'details of construction, all of which willbe made clear during the' course ofthe following specification, referring to the accompanying drawing wherein:

Fig. l is an end elevational view of a renewable fuse plug, made in accordance with the present invention.'

' ',Fig. `2 is a longitudinal central sectional View through the renewablefuse plug, taken on line II-II of Fig. 1.

Fig. 3 is a composite stretch-out perspective view showing thel component parts of the fuse plug.

Fig. 4 is a cross sectional View taken on line IV-IV of Fig'. 2.

Fig. 5 isa cross sectional view taken on line V-V of Fig. 2; and

Fig. 6isa stretch-out plan view of the fusible element forming a part of the plug.

Fuse plugs having renewable fusible elements have been-heretofore designed and placed on the market, but' inmost instances, the same do not meet the stringent requirements of authorities and commercial use, and further, fail because of faulty structurel and part design. It is also understood that many fuse plugs having renewable elements have been produced but found ineffectivebecause of complicated parts, and the obvjectio'nable amount of time and Work required to disassemble and assemble the plug when replacing'the fusible element.

It is the prime object of this invention therefore, to produce a screw plug for the conventional fuse box `I5 that may be removed from said box, when lnecessary to have the fusible element 8 renewed, and thereafter, quickly taken apart and reassembled with a fresh fusible element.

The plug comprises a thimble-shaped body I0,

preferably produced of glass or other transparent material in order that the user may readily observe when element 8 has been melted. Element 8 is provided with a partial coating of substance I2, which, when dispersed by heat, will create a colored coating' on the inner surface of body IEI.

External threads I4 on body l) cooperate 'with threaded cylinder I6, made of conducting material, and provided with an inturned 'annular flange I8, overhanging the lip of body Ill, as illusrtrated -in Fig. 2'.' Flange I8 has an integral, ringshaped boss I'I on the free marginal edge thereof, the upper face of which is roughened to provide teeth against which'the, later described perforated plate 3o rests when the parts are assembled. The undulated annulary side wall of cylinder |46 not only serves to engagelthe threads Iii of body if?, but presents threads to enter the socket formed in fuse box 6.

' "A plug I9 of insulating material has a longitudinal bore 2o and a transverse laterallydisposed cavity 22. Longitudinal bore 2G and cavity 22 intersectas clearly shown in Fig. 2, and for the purpose hereinafter specied. Plug VI9 has an annular external ange 24 at one end thereof and a boss 26 on the upper surfacawhich surface is a part of plug I9 projecting outwardly from`withn thimble-shaped body Il! when Athe component parts of the plug are'assembled.

A notch 28 Jformed in flangezfi terminates on a plane with a flattenedrarea Y2l on the annular periphery of plugwIS, to receive a portion of the lengthof flexible element 8 when it is wrapped about the plug. Another flattened area 23,4 diametricaly opposite to ZI is engaged by another portion of the length of element 8 as shown in Fig. 2. A third flat face 25 on plug i9 lies against a complementary flattened portion 2'l on the Perforated plater30 of insulating material overlies boss II of cylinder I6 when threadedcontact post 32 is moved to place.

Flexible element 8 has a nut 34 secured to that end thereof which projects into cavity'22. This rnut is of conventional character and in commercial practice, may be soldered directly to the end of element 8 so that the screw-threaded opening 'x36 thereof lies in alignment with bore 2S when Acreated thereon to circumscribe bossv `When annulus 3S is in such position, with respect to boss 26, displacement cannot occur and flange i8 cf cylinder I6 will be pressed directly against one face of annulus 38 by force exerted on plate 3G by contact post S2. Reference to Fig. 2 indicates how plate 38 is received by the roughened upper surface of boss I1 and how the height of this boss precludes plate 3S from engaging the top of boss 26 on plug I9.

Flange 24 of plug I9 lies between flange I8 and the lip of body I0, and as post 32 is turned into threaded engagement with opening 35 of nut 34, all of the fuse plug parts will be drawn together with positive electrical contacts where most needed. The contact between cylinder l and annulus 38 is maintained by the full force of post 32 and no danger of loosening is present. Due to the roughened surface on boss l1, plate 3f) cannot turn as post 32 is either tightened or loosened. As the post is turned, plug I9 is held against rotation with respect to body l0 by flattened areas and 2l. The contact between post 32 and nut 34 is ample in View of the screwthreaded relation between the parts, and therefore, a definite electrical connection is established between the contact members of box 6 when the fuse is in place, as shown in Fig. 2.

It is obvious from the foregoing that one may very quickly remove and disassemble the entire fuse plug, replace a melted fuse element 8, and again position the plug without creating the danger of wrong connections.

Not only is a fuse plug embodying this invention efficient, easy to manipulate, and desirable from the users standpoint, but may be made at very low cost, both as regards material and labor.

Minor changes might be made to present fuse plugs having physical characteristics different from those illustrated and described, and it is therefore, desired to be limited only by the spirit of the invention and scope of the appended claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. A fuse plug of the character described comprising a hollow body of insulating material; a plug of insulating material projecting into the hollow body and provided with two intersecting bores; a fusible element partially circumscribing the plug and having one end thereof extending into one bore of the plug and the other end disposed against the outer portion of the plug; a cylinder of conducting material in telescoping relation with the body and bearing against a length of the fusible element at the said other end thereof; a perforated plate of insulating material; and a contact post of conducting material tted through the perforation of the plate, into the other bore and into engagement with the fusible element.

2. A fuse plug of the character described comprising a hollow body of insulating material; a plug of insulating material projecting into the hollow body and provided with two intersecting bores; a fusible element partially circumscribing the plug and having one end thereof extending into one bore of the plug and the other end disposed against the outer portion of the plug; a cylinder of conducting material in telescoping relation with the body and bearing against a length of the fusible element at the said other end thereof; a perforated plate of insulating material; and a contact post of conducting material tted through the perforation of the plate into the other bore and into engagement with the fusible element, said fusible element and the contact post being in screw-threaded engagement whereby upon rotation of the post, said plate is drawn against the cylinder to grip the one end of the fusible element between the cylinder and said plug.

3. A fuse plug of the character described comprising a hollow body of insulating material; a plug of insulating material projecting into the hollow body and provided with two intersecting bores; a fusible element partially circumscribing the plug and having one end thereof extending into one bore of the plug, and the other end disposed against the outer portion of the plug; a cylinder of conducting material in telescoping relation with the body and bearing against a length of the fusible element at the said other end thereof; a perforated plate of insulating material; and a contact post of conducting material fitted through the perforation of the plate, into the other bore and through the fusible element, said contact post and fusible element being in screw-threaded engagement whereby to removably anchor the element in position.

4. A fuse plug of the character described comprising a hollow body of insulating material; a. plug of insulating material projecting into the hollow body and provided with two intersecting bores; a fusible element partially circumscribing the plug and having one end thereof extending into one bore of the plug and the other end disposed against the outer portion of the plug; a cylinder of conducting material in telescoping relation with the body and bearing against a length of the fusible element at the said other end thereof; a perforated plate of insulating material; and a contact post of conducting material fitted through the perforation of the plate, into the other bore and into engagement with the fusible element, the said other end of the fusible element having an annulus thereon to circumscribe a part of the outer portion of the plug, the said one end of the fusible element being a head thereon provided with an opening to receive the contact post.

5. A fuse plug of the character described comprising a hollow body of insulating material; a plug of insulating material projecting into the hollow body and provided with two intersecting bores; a fusible element partially circumscribing the plug and having one end thereof extending itno one bore of the plug and the other end disposed against the outer portion of the plug; a cylinder of conducting material in telescoping relation with the body and bearing against a length of the fusible element at the said other end thereof; a perforated plate of insulating material; and a contact post of conducting material fitted through the perforation of the plate, into the other bore and into engagement with the fusible element, said plug having a boss on the outer end thereof, the said other end of the fusible element having an annulus thereon to circumscribe the boss, the said one end of the fusible element having an opening to receive the contact post.

6. A fuse plug of the character described comprising a hollow body of insulating material; a plug of insulating material projecting into the hollow body and provided with two intersecting bores; a fusible element partially circurnscribing the plug and having one end thereof extending into one bore of the plug and the other end disposed against the outer portion of the plug; a cylinder of conducting material in telescoping relation with the body and bearing against a length of the fusible element at the said other end thereof; a perforated plate of insulating material; and a contact post of conducting material tted through the perforation of the plate, into the other bore and into engagement with the fusible element, said plug having a boss on the outer end thereof, the said other end of the fusible element having an annulus thereon to circuinscribe the boss, the said one end of the fusible element having an opening to receive the Contact post, said cylinder having an internal ange overlying the annulus of the fusible element and circumscribing the boss on the plug, said plate being held against the flange of the cylinder by the contact post.

7. A fuse plug of the character described comprising a hollow body of insulating material; a plug of insulating material projecting into the hollow body and provided with two intersecting bores; a fusible element partially circurnscribing the plug and having one end thereof extending into one bore of the plug and the other end disposed against the outer portion of the plug; a cylinder of conducting material in telescoping relation with the body and bearing against a length of the fusible element at the said other end thereof; a perforated plate of insulating material; and a contact post of conducting material tted through the perforation of the plate, into the other bore and into engagement with the fusible element, said plug having a boss on the outer end thereof, the said other end of the fusible element having an annulus thereon to circumscribe the boss, the said one end of the fusible element having an opening to receive the contact post, said cylinder having an internal flange overlying the annulus of the fusible element and cirournscribing the boss on the plug, said plate being held against the ange of the cylinder by the contact post, said plug having an external ange resting on the lip of the thirnble, said thirnble and cylinder being in screw-threaded engagement.

S. As a new article of manufacture, a fusible element for fuse plugs, comprising an elongated body; an annulus formed at one end of the body; and a nut secured to the other end of the body.

9. In a fuse plug of the character described, a plug provided with tWo intersecting bores; a fusible element partially circurnscribing the plug with one end projecting into one of the bores; a threaded contact post projecting into the other bore; and a nut carried by the said one end of the fusible element, in screwthreaded engagement with the Contact post.

EMILE P. BRUS. 

